<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.7.10/dist/vue.min.js"></script>
</head>

<body>
    <div id="app">
        <input type="text" v-model="msg">
        <h1>{{msg | filterB}}</h1>
    </div>
</body>
<script>
    Vue.filter("filterB", function(value) {
        if (value != '' && value != null) {
            const num = parseFloat(value).toFixed(2);
            return num + '元'
        }

    })
    var vue = new Vue({
        el: '#app',
        data: {
            msg: ''
        }
    })
</script>

</html>